From Kinetics to Proteomics: Unraveling the Mechanisms of Iron Uptake in Marine Diatoms
Event Format: Hybrid Webinar (Zoom and in-person)
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Speaker: Dr. Adam Kustka, Rutgers University
Core metabolic pathways likely emerged in early Earth history when iron was readily available. This, and iron’s exquisite redox flexibility is consistent with the quantitative importance of iron among all the transition metals co-opted by life. Subsequent planetary oxygenation dramatically decreased iron availability in the oceans, setting the stage for competition and selective pressure for high affinity iron uptake among prokaryotic and eukaryotic marine microbes. Our group has been working towards resolving mechanisms of iron uptake in marine eukaryotic phytoplankton. These efforts first relied on carefully controlled kinetic experiments when genomic tools or even sequenced genomes were not yet available, but more recently leverag reverse genetics and proteomics. We’ve focused on characterizing two iron uptake systems, the reductive-oxidative pathway best described in yeast and a “phytotransferrin” pathway that shares features in common with mammalian transferrin. In the centric diatom, Thalassiosira pseudonana, our data suggests the ferric permease may engage in direct ferric ion uptake; this apparent departure from canonical permease behavior in yeast is consistent with this diatom’s autecology. Phytotransferrin is widely represented among “red lineage” marine algae, including in the model diatom Phaeodactylum tricornutum, where phytotransferrin-mediated high affinity iron uptake is susceptible to ocean acidification.